1. Field of the Invention
The present invention relates to a tilt cord controller for venetian blinds, e.g., vertical venetian blinds, for preventing damage to transmission elements due to excessive pulling force acting on the tilt cord.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a tilt cord controller for venetian blinds for controlling tilt angle of the blind. The tilt cord controller includes a casing 21 consisting of two casing halves 211 and 212, wherein casing half 212 includes a tubular member 213 for rotatably holding a rotating member 214, and casing half 211 is used to rotatably support a pulley 22 around which a tilt cord (not shown) is wound around. The pulley 22 includes a stud 221 with annularly spaced longitudinal ridges 222 formed on an outer periphery of the stud 221. The rotating member 214 includes a plurality of annularly spaced grooves (not shown) in an inner periphery defining a longitudinal hole 215 thereof for securely engaging with the ridges 222. Thus, pulling of the tilt cord causes rotation of the pulley 22, which, in turn, drives the tilt rod (not shown) via transmission by the rotating member 214. Nevertheless, it is found that the pulley 22 and the rotating member 214 and other transmission elements are damaged easily if the tilt colt is pulled by an excessive force which still forces the tilt rod to turn although the tilt rod has reached its end position. Longevity of the tilt cord controller is thus shortened.